About 6 calories each or so (if you mean M&M the chocolate candy). If you meant millimeter, there is no relationship between calories and millimeters.
260 calories
According to one online resource, one m&m has about 4.5 calories, 0.2g fat and 0.6g carbs.
10 mm = 1cm 1 in = 2.54 cm 1 in = 25.4 mm
90 mm
16.5 mm
6450 mm
100 mm
153 mm
760 mm
50.8 mm
304.8 mm
8500 mm